Metal clad circuit-breakers for high voltages



United States Patent 3,22%)57 METAL CLAD CIRCUIT-BREAKERS FOR HIGH VOLTAGES Arend de Rutter, Utrecht, Netherlands, assignor to N.V. COQ, Utrecht, Netherlands, a company of the Netherlands Filed June 10, 1963, Ser. No. 286,738 Claims priority, application Netherlands, June 13, 1962, 279,630 3 Claims. (Cl. 200-50) The invention relates to a metal clad circuit-breaker for high voltages having at least one switching element comprising an axially movable switching rod, a slide contact permanently connected therewith and a fixed switch contact cooperating with the switching rod, said switching element being accommodated in an earthed casing closed by a cover containing the driving mechanism, said switching element being attached to said cover and, when the circuit-breaker is in its normal operating position, detachably connected through its slide contact and its fixed switch contact to fixed terminal contacts provided in the casing and electrically conductively connected to the connecting conductors of the circuit-breaker and said switching element being adapted, when the cover together with the driving mechanism is removed from the casing or disposed thereupon, to be removed from and inserted into the casing, respectively, while said terminal contacts and the connecting conductors are alive.

If in known circuit-breakers of this type measurements have to be carried out on the cable connected to such a circuit-breaker, the switching rod must be removed from the switching element when the latter is in its normal operating position and instead thereof a measuring rod provided with terminals for the connection of the measuring apparatus must be inserted into the circuit-breaker. Before it is allowed to insert said measuring rod into the circuit-breaker one must make sure that the cable to be measured is dead. For the sake of safety it is mostly required that the cable is connected to earth before measurements are carried out. Consequently, for this purpose one or more earthing switches must be used in combination with such a circuit-breaker or group of such circuit-breakers. Also on other grounds than to perform measurements it is often necessary that the cable is connected to earth at its end connected to the circuit-breaker. The invention has for its object to make the use of individual earthing switches superfluous. It consists in that two additional fixed terminal contacts are provided in the casing, of which the mutual distance in axial direction is equal to that between the slide contact and the fixed switch contact of the switching element, one of said additional terminal contacts lying between the two first mentioned terminal contacts and being connected to earth and the other one thereof being electrically conductively connected to the terminal contact which is electrically conductively connected through the slide contact to the switching rod, when the circuit-breaker is in its normal operating position, whereas means are provided, which permit the cover together with the driving mechanism to be moved from and the switching element to be partly lifted out of the casing and to be placed in an intermediate position, in which intermediate position the switching element is connected through its slide contact and its fixed switch contact to the additional terminal contacts. In this case the circuit-breaker itself may thus be used as earthing switch, so that the additional advantage is obtained that, should the circuit-breaker be an automatic circuit-breaker, the earthing switch is controlled by the safety device thereof and is automatically opened, should a live cable be connected to earth by said circuit-breaker. These and other features of the invention will be described herebe- 3,229,057 Patented Jan. 11, 1966 low with the aid of the accompanying drawing. In the drawing is:

FIG. 1 a vertical cross sectional view of a circuitbreaker according to the invention, of which the switching element is in its normal operating position and FIG. 2 a vertical sectional cross section of the same circuit-breaker, the switching element of which is in a position allowing measurements to be carried out.

In the drawing 1 is a metal casing, in which a tube 2 of insulating material is mounted. The space 3 within the casing 1 and outside the tube 2 is filled with liquid or gaseous insulating material. This space contains at the same time busbars 4, to which a number of the illustrated circuit-breakers, all of which may be contained in the casing 1, are connected. Provided within the tube 2 is a switching element consisting of an axially movable switching rod 5, a slide contact 6 permanently connected with said rod and a fixed switch contact 7 cooperating with the switching rod 5. The contacts 6 and 7 are kept spaced apart by a tube 8 of insulating material. The switching element is attached by a tube 9 of insulating material to a cover 10, in which the driving mechanism for the switching rod and diagrammatically shown by the dotted lines 11 is accommodated. This driving mechanism is provided with an operating lever pivotally mounted on an axle 12, said lever being swung upwards, when the circuit-breaker is in its switched-off position, and swung downwards into the position 13 shown in dotted lines, when the circuit-breaker is in its switched-on position.

In the normal operating position of the circuit-breaker shown in FIG. 1 the slide contact 6 is detachably electrically conductively connected to a terminal contact 14, to which a connecting conductor 16 used for the connection of the circuit-breaker to a cable and passed through an insulator 15 to the outside is connected. Furthermore the fixed switch contact 7 is detachably electrically conductively connected to a terminal contact 17, to which a bar of the busbars 4 is directly connected. The terminal contacts 14 and 17 are provided on the inner surface of the insulating tube 2 and they make it possible, that the switching element is removed from the casing 1 and inserted therein, while the terminal contacts 14 and 17 are alive.

In accordance with the invention additional terminal contacts 18 and 19 are mounted in the tube 2. The mutual distance of these terminal contacts equals that between the slide contact 6 and the fixed switch contact 7. The terminal contact 18 is electrically conductively connected to the terminal contact 14 and the terminal contact 19 is connected by a metal plate 20 to the casing 1, that means is connected to earth.

The cover 10 together with the driving mechanism 11 and the switching element 5, 6, 7, 8, 9 is adapted to be positioned in the intermediate position shown in FIG. 2, in which intermediate position the switching element is partly lifted out of the casing and conductively connected through the slide contact 6 to the terminal contact 18 and through the fixed switch contact 7 to the terminal contact 19, consequently through the plate 20 and the casing 1 to earth. In this intermediate position the circuit breaker itself is used to earth the cable connected to the connecting conductor 16. To that end the circuitbreaker need only be switched on.

In order to move the circuit-breaker from its normal operating position into the intermediate position the cover 163 is provided with slides 21 mounted for sliding on a guiding column 22 provided on the casing 1. More over, the cover 10 is coupled in the pivot 23 with a bow shaped lever 24 which is connected through links 25 to a fixed pivot 26 of the casing. The lever 24 permits the cover and accessories to be moved up and down and the circuit-breaker to be moved from the normal operating position into the intermediate position and vice versa.

In order to lock the circuit-breaker in the said positions a locking member 28 loaded by a spring 27 and adapted to be released by hand is provided, said locking member being forced by the spring 27 into a recess 29 or 30 and locking thereby the circuit-breaker in the relevant position.

Since it must be prevented that the circuit-breaker, when in its switched-on position, is moved out of its normal operating position a locking pin 31 is attached to the operating lever 13, said locking pin blocking the locking member 28 in the locking position thereof, when the operating lever is in the position 13' corresponding with the switched-on position of the circuit-breaker. Consequently the circuit-breaker can only be moved up and down by means of the lever 24, when it is in its switchedoif position.

If it is desired for purposes of inspection to lift the circuit-breaker entirely out of the casing 1, the lever 24 must be detached from the casing 1 in a manner not shown. To that end the pivot 26 could be easily detachably connected to the casing.

It is observed that the plate 20 forms at the same time an earthed screen between the cable connected to the connecting conductor 16 and the busbars 4, whereby the safety in the casing of the circuit-breaker is increased.

In order to allow the required measurements a measuring rod 32 is inserted in the circuit-breaker, when the latter is in the intermediate position. By means of said measuring rod the terminal contact 18 is electrically conductively connected to a connecting bolt 33 provided with nuts 34 and projecting from the circuit-breaker to the outside. The measuring apparatus is then connected to the bolt 33 and, through the measuring rod 32, the terminal contact 18, the terminal contact 14 and the connecting conductor 16, to a cable to be measured.

What is claimed is:

1. A high tension metal clad circuit breaker comprising an elongated metal casing for electrical connection to earth, a box-like cover detachably closing one end of said casing, a driving mechanism provided in said cover, at least one composite switching element attached to said cover and removably accommodated in said casing, said composite switching element including at least one mov able switching rod mechanically connected to said driving mechanism, at least one slide contact in permanent contact with said switching rod and insulatedly connected to said cover, and at least one switching contact spaced below and insulated from the slide contact for switching contact with said rod, at least one lead-in conductor insulatedly passed through a wall of the casing for the connection of one end of a circuit to be controlled by the circuit breaker, at least one first fixed terminal contact in said casing and conductively connected to said lead-in conductor, at least one second fixed terminal contact in said casing for the connection of the other end of a circuit to be controlled by the circuit breaker, said first and said second fixed terminal contacts being in contact with the slide contact and the switching contact of the switching element respectively when the switching element is disposed in the casing in the normal operational position of the cover when the cover engages and closes the easing, at least one set of two additional fixed terminal contacts disposed in the casing to make sliding contact with said composite switching element, the longitudinal distance between said additional terminal contacts being substantially equal to the distance between the slide contact and the switching contact of the switching element, one of said additional terminal contacts being positioned between said first and second terminal contacts and being electrically conductively connected to said metal casing for connection to earth, the other of said additional terminal contacts being electrically conductively connected to said first terminal contact, said cover carrying the driving mechanism and the switching element being longitudinally movable to an intermediate position spaced from the casing by a distance substantially equal to the distance between the second terminal contact and said one additional terminal contact, and means for locking the cover in said intermediate position whereby the switching element protectively connects said lead-in conductor to earth as a circuit breaker.

Z. A high tension metal clad circuit breaker according to claim 1 further comprising at least one guiding column extending parallel to said switching rod and attached to said end of the casing closed by the cover, a slide on said cover engaging said column for guiding the cover in its movement to said intermediate position, a lever coupled both with the casing and with the cover and serving to move the cover together with the driving mechanism and the switching element to both the said intermediate and normal operational positions, said means for locking the cover including a locking member on the cover releasably engageable with spaced detents on said guiding column for locking the cover in both said intermediate and normal operational positions.

3. A high tension metal clad circuit breaker according to claim 2 further comprising a handle movably mounted on said cover and mechanically connected to said driving mechanism for moving said switching rod to switched on and off conditions, said handle when moved to a position for placing the switching rod in switched on condition engaging said locking member to hold the latter in one of said detents to lock the cover in its normal operational position.

References Cited by the Examiner UNITED STATES PATENTS 1,933,506 10/1933 Noyes 200l63 2,458,792 1/1949 Nijland 200l3 X 2,689,293 9/1954 Claybourn 200- X KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. A HIGH TENSION METAL CLAD CIRCUIT BREAKERS COMPRISING AN ELONGATED METAL CASING FOR ELECTRICAL CONNECTION TO EARTH, A BOX-LIKE COVER DETACHABLY CLOSING ON END OF SAID CASING, A DRIVING MECHANISM PROVIDED IN SAID COVER, AT LEAST ONE COMPOSITE SWITCHING ELEMENT ATTACHED TO SAID COVER AND REMOVABLY ACCOMMODATED IN SAID CASING, SAID COMPOSITE SWITCHING ELEMENT INCLUIDNG AT LEAST ONE MOVABLE SWITCHING ROD MECHANICALLY CONNECTED TO SAID DRIVING MECHANISM, AT LEAST ONE SLIDE CONTACT IN PERMANENT CONTACT WITH SAID SWITCHING ROD AND INSULATEDLY CONNECTED TO SAID COVER, AND AT LEAST ONE SWITCHING CONTACT SPACED BELOW AND ISULATED FROM THE SLIDE CONTACT FOR SWITCHING CONTACT WITH SAID ROD, AT LEAST ONE LEAD-IN CONDUCTOR INSULATEDLY PASSED THROUGH A WALL OF THE CASING FOR THE CONNECTION OF ONE END OF A CIRCUIT TO BE CONTROLLED BY THE CIRCUIT BREAKER, AT LEAST ONE FIRST FIXED TERMINAL CONTACT IN SAID CASING AND CONDUCTIVELY CONNECTED TO SAID LEAD-IN CONDUCTOR, AT LEAST ONE SECOND FIXED TERMINAL CONTACT IN SAID CASING FOR THE CONNECTION OF THE OTHER END OF A CIRCUIT TO BE CONTROLLED BY THE CIRCUIT BREAKER, SAID FIRST AND SAID SECOND FIXED TERMINAL CONTACTS BING IN CONTACT WITH THE SLIDE CONTACT AND THE SWITCHING CONTACT OF THE SWITCHING ELEMENT RESPECTIVELY WHEN THE SWITCHING ELEMENT IS DISPOSED IN THE CASING IN THE NOMAL OPERATIONAL POSITION 